1. Field of the Invention
The present invention relates to a method and apparatus to disturb an unwanted radiated voice signals from communication device, and more particularly, to a method and/or apparatus to generate and output disturbing sound so that a phone speech signal that is supposed to be only heard by parties who are currently engaging in a phone conversation (so called active listener) cannot be recognized by third parties (so called passive listener).
2. Description of the Related Art
The privacy of phone conversations conducted using mobile phones or landline phones in offices sometimes may not be fully guaranteed depending on the situation of users who are conversing on the phone. Users must walk out of earshot of the surrounding parties in order to prevent their phone conversations from being heard to the third parties. Therefore, techniques of preventing phone speech from being heard to the third parties are necessary. Sometimes, users have to have a phone conversation even when the users cannot walk away from the third parties such as when they are in a vehicle with the third parties or the users are answering the phone in the middle of a conference. In this case, the third parties can listen to the phone conversation that may contain personal or confidential information.
U.S. Patent Publication Application No. 2003-0048910 discloses a method of masking sounds within enclosed spaces. According to this sound masking method, a sound masking system is attached onto the ceiling of an enclosed space, and masks sounds generated within the enclosed space. This sound masking method simply modulates voice by masking sounds generated within an enclosed space. Thus, this sound masking method is not suitable for masking sounds in a mobile environment.
In addition, Korean Patent Laid-Open Gazette No. 2003-22716 discloses a sound masking system which can be installed near a speaker of a telephone receiver. This sound masking system requires a user to place a telephone receive in firm contact with his/her ear in order to prevent an incoming voice signal from being heard to third parties. However, due to the properties of sound waves, it is hard to completely prevent an incoming voice signal from being heard externally no matter how hard the user tries to have a private or confidential phone conversation. Thus, there is always a probability that the content of a phone conversation can be recognized by the third parties.
Given all this, it is necessary to develop methods and systems which can guarantee the privacy of phone conversations without requiring a user to walk away from the surrounding parties and prevent phone conversations, particularly, those containing confidential information from being heard by other parties. In other words, methods and systems capable of preventing the content of a phone conversation from being heard by other parties while not interfering with those who participate in the phone conversation are required.